The invention concerns a multi-layer body in the form of a multi-layer film, preferably a transfer film or a laminating film or in the form of a layer composite laminated from at least one overlay film and preferably an inlet, with a laser-sensitive layer. The invention further concerns a process for producing a multi-layer image in such a multi-layer body.
Bodies which comprise laser-sensitive material are known. For example WO 96/35585 discloses various configurations of plastic bodies, more specifically in the form of a solid body or coating, which each contain a mixture of various pigments. Color marking is effected by laser treatment on the plastic body or in the coating.
WO 98/19868 describes a process which operates with specific yellow, magenta and cyan pigments which can be activated in a first step by way of UV light and which are bleached only in a subsequent second step.
DE 199 55 338 also discloses a process for producing color markings by laser treatment when using a mixture of cyan pigment, magenta pigment and yellow pigment, wherein those pigments are selectively bleached by red laser light, green laser light and blue laser light. That process is described for the use of a plastic body made from a material with the pigment mixture in question.
It is also known from WO 94/12352 to produce multi-colored markings by laser treatment using different wavelengths, on a plastic body which includes a pigment mixture and which can be in the form of a solid body and a coating. The coloration operation is effected by virtue of the pigments changing their color due to a color change in the laser treatment. EP 0 327 508 discloses a process in which a laser-sensitive dye A and a laser-insensitive dye B are contained in two separate, mutually superposed layers or alternatively in a common layer, and the dye A is bleached by laser treatment. Thus the laser treatment affords a color marking which however only involves a change in color of the dye A, and therefore only a maximum two-color image is obtained.
EP 0 190 997 B1 discloses a process in which a plastic layer in the form of a covering on a metal plate portion or a plastic plate contains an additive which is intended to change in color when subjected to a laser treatment, more specifically either by a color change from one color to another or by transformation into black.
DE 37 38 330 A1 discloses a laser labelling process for use in relation to a surface pigment coating, wherein pigments of the pigment coating change their internal molecular structure at different temperatures and furnish different colors. The specific surface temperatures are locally achieved with the laser radiation, whereby laser markings are obtained.
GB 2 240 948 A also discloses the laser labelling of identity cards. Here laser labelling is effected by the removal of different color layers. The laser marking which is obtained in that case appears in the form of a colored marking.
DE 41 31 964 A1 describes laser labelling on a multi-layer film with a metal layer and a hologram structure. The labelling procedure is implemented by region-wise destruction of the metal layer bearing the hologram.
EP 0 420 261 discloses a hot stamping film with a hologram structure which is individualised by way of laser treatment for the purposes of affording a safeguard against forgery. A change in material or color or removal of partial regions in the layer structure of the film is implemented by means of the laser beam.
EP 0 219 011 B1 describes a specific process for the laser labelling of identity cards. In that process black markings are produced in various transparent layers of the card by means of the laser. In that way parallax images are obtained in the mutually co-operating transparent layers.